Multicast and Broadcast Service (MBS) provides point-to-multipoint service transmitting data from one data source at the network side to multiple mobile terminals in a mobile network, so that network resources are shared and the utilization rate of the network resources is improved, especially the utilization rate of air interface resources. Further, the MBS is capable of implementing not only the multicast and broadcast for a pure-text and low-rate service such as a message, but also the multicast and broadcast for a high-rate multimedia service, and thus the MBS conforms to the trend of mobile data development. Therefore, the MBS has a vast range of prospects.
In the MBS, for the purpose of reducing power consumption of a mobile terminal, a sleep mode of the mobile terminal is provided. During sleep duration, e.g. a sleep window, agreed in advance by both the mobile terminal and a base station, the mobile terminal stays in a sleep state, the air interface disconnects with the base station temporarily, and the mobile terminal neither sends nor receives any service information; only during a listening duration agreed in advance by both the mobile terminal and the base station, the mobile terminal stays in a listening state and receives MBS data normally. Therefore, by applying the sleep mode of the mobile terminal, transmission requests of the mobile terminal in both an uplink and a downlink are reduced, and thus the power consumption of the mobile terminal is reduced.
In the MBS, when being in the sleep mode, the mobile terminal is capable of receiving the MBS data in a non macro diversity manner. In the non macro diversity manner, for the purpose of receiving the MBS data accurately by the mobile terminal, the base station transmits to the mobile terminal a Downlink Resource Allocation (DL_MAP) message carrying an MBS Mapping Information Element (MBS_MAP_IE) when transmitting a frame of the MBS data to the mobile terminal. The format of the MBS_MAP_IE is shown in table 1.
TABLE 1SyntaxSize(bits)NotesMBS_MAP_IE{——Extended-2 DIUC4extended DIUC typeLength8length of the MBS_MAP_IEMBS Zone identifier7MBS Zone identifier corresponding to theidentifier provided by the BS at connectioninitiationMacro diversity enhanced1Macro diversity enhanced indication:0 = Non Macro-Diversity enhanced zone1 = Macro-Diversity enhancedIf(Macro diversity enhanced =1){Permutation20b00 = PUSC permutation0b01 = FUSC permutation0b10 = Optional FUSC permutation0b11 = Adjacent subcarrier permutationIdcell6Cell identityOFDMA Symbol Offset7OFDMA symbol offset from the start of theMBS zone to the start of the current frameDIUC change indication1DIUC change indicationif (DIUC change indication =——1) {Reserved1Reserved bitBoosting3Power boost000: not boosted; 001: +6 dB;010: −6 dB; 011: +9 dB;100: +3 dB; 101: −3 dB;110: −9 dB; 111: −12 dBDIUC3—No. Subchannels4the number of subchannels occupied by theMBS_MAP messageNO. OFDMA symbols2the number of OFDMA symbols occupiedby the MBS_MAP messageRepetition Coding Indication2Repetition Coding Indication:0b00 - No repetition coding0b01 - Repetition coding of 20b10 - Repetition coding of 40b11 - Repetition coding of 6}——}else{DIUC4—CID12 the last 12 bits of MBS connection numberOFDMA Symbol Offset8OFDMA symbol offset from the MBScorresponding to CID to the start of thecurrent frameSubchannel offset6subchannel offset from the MBS servicecorresponding to CID to the start of thecurrent frameBoosting3Power boost000: not boosted; 001: +6 dB;010: −6 dB; 011: +9 dB;100: +3 dB; 101: −3 dB;110: −9 dB; 111: −12 dBSLC_3_indication1sleep indication informationNO. OFDMA Symbols6the number of OFDMA symbols occupiedby the MBS corresponding to CIDNO. Subchannels6the number of subchannels occupied by theMBS corresponding to CIDRepetition Coding Indication2repetition Coding Indication:0b00 - No repetition coding0b01 - Repetition coding of 20b10 - Repetition coding of 40b11 - Repetition coding of 6if(SLC_3_indication = 1) {——Next MBS frame offset8the offset from the next frame including anMBS_MAP message to the current frameNext MBS OFDMA Symbol8OFDMA symbol offset from the nextoffsetMBS_MAP message to the start of theframe including the next MBS_MAPmessage}——}——if !(byte boundary) {——Padding NibblePad to Byte boundary}}
With reference to table 1, when the mobile terminal is in the sleep mode and receives the MBS data in the non macro diversity manner, the MBS_MAP_IE transmitted to the mobile terminal by the base station carries the parameters for indicating the specific MBS resources, OFDMA Symbol Offset and Subchannel offset. The parameter OFDMA Symbol Offset indicates the symbol offset of the MBS data in the data frame currently received, and the parameter Subchannel offset indicates the subchannel offset of the MBS data in the subchannel of the data frame currently received. The parameter NO.OFDMA Symbols indicate the number of symbols occupied by the MBS data, and the parameter NO. Subchannels indicate the number of subchannels occupied by the MBS data. In this way, according to the parameter OFDMA Symbol Offset, the parameter Subchannel offset, the parameter NO.OFDMA Symbols and the parameter NO. Subchannels, the mobile terminal may acquire the MBS resources and receive the MBS data accurately.
With reference to table 1, when the mobile terminal is in the sleep mode and receives the MBS data in the non macro diversity manner, the MBS_MAP_IE transmitted to the mobile terminal by the base station further carries the parameter SLC_3_indication=1 for indicating that the mobile terminal adopts the sleep mode and the frame position of the next Multicast and Broadcast Service Mapping (MBS_MAP) message needs to be indicated. Moreover, the MBS_MAP_IE correspondingly carries parameters for indicating the receiving position of the next MBS_MAP message, Next MBS frame offset and Next MBS OFDMA Symbol offset. Here, the parameter Next MBS frame offset indicates the frame offset from the next MBS_MAP message to the data frame currently received, and the parameter Next MBS OFDMA Symbol offset indicates the symbol position of the next MBS_MAP message, i.e. the symbol offset from the next MBS_MAP message to the header of the frame including the next MBS_MAP message. In this way, according to the parameters Next MBS frame offset and Next MBS OFDMA Symbol offset carried in the MBS_MAP_IE currently received, the mobile terminal wakes up to listen to the MBS_MAP message in subsequent processes. According to the relevant information carried in the MBS_MAP message currently received, the mobile terminal determines the next MBS resources so as to acquire the next MBS data.
It can be seen from the above description, in the conventional technologies, when the mobile terminal is in the sleep mode and receives the MBS data in the non macro diversity manner, the base station indicates the MBS resources repetitively. The reason is as follows: in the MBS_MAP_IE currently received from the base station, the definition of the parameter SLC_3_indication=1 indicates that the frame position of the next MBS_MAP message needs to be indicated, and the parameters Next MBS frame offset and Next MBS OFDMA Symbol offset indicates the receiving position of the next MBS_MAP message; the next MBS_MAP message sent by the base station to the mobile terminal indicates the next MBS resources; accordingly, the mobile terminal has to wake up to receive the next MBS_MAP message in the subsequent processes so as to obtain the next MBS resources through the MBS_MAP message. However, in the next MBS_MAP_IE sent by the base station, the parameters OFDMA Symbol offset and Subchannel offset also indicates the next MBS resources. Therefore, the base station indicates the MBS resources repetitively. But the mobile station not only has to wake up to acquire the MBS resources when receiving the MBS_MAP_IE, but also has to wake up to acquire the MBS resources again when receiving the MBS_MAP message, and the MBS resources acquired respectively when receiving the MBS_MAP_IE and the MBS_MAP message are identical. Therefore, the sleep duration of the mobile terminal is reduced, the power consumption of the mobile terminal increases, and mobility of the mobile terminal decreases.